Rumour has it that Apple will delay iOS 5, the upcoming version of its iPhone operating system, until the fall, but that would make the iPhone 5 a tough sell if it still launches this summer.

Rumor has it that Apple will delay iOS 5, the upcoming version of its iPhone operating system, until the fall, but that would make the iPhone 5 a tough sell if it still launches this summer.

Here's how the iPhone and iOS launches worked last year: Apple announced major changes to iOS in April, including multitasking, app folders, and a unified inbox. Then in June, Apple announced the iPhone 4 at the Worldwide Developers Conference. Both the iPhone 4 and iOS 4 arrived later that month.

Take a look at the current feature page for the iPhone 4. One of the most prominently advertised features is multitasking, which is part of iOS 4 and not tied to the iPhone 4 specifically. Software was an even bigger emphasis for the iPhone 3GS, whose old product page mentioned voice control, a compass, copy and paste and a landscape keyboard as major selling points.

That's why I'm skeptical of TechCrunch's claim that Apple will launch the next iPhone with iOS 4.x, saving a more substantial software upgrade for the fall. Without a new OS, the iPhone 5 will lack new features for Apple to advertise, and it's just not Apple's style to release a product with an IOU for unreleased benefits.

Some earlier reports suggest that Apple will hold off on the iPhone 5 until the fall, which to me seems likely if iOS 5 will be delayed as well. There are also rumors of a cheaper, possibly smaller iPhone that would launch separately from the iPhone 5. Maybe that's what we'll see in the summer. At this point, it's anybody's guess, but one thing's certain: If Apple launches the iPhone 5 without a software update to match, it'll be a big letdown.